Evaluation of Fat Quantification in the Liver Using Dual Energy CT.

BACKGROUND AND PURPOSE: Recently, the number of patients with nonalcoholic fatty liver disease (NAFLD) has been increasing, and some of them progresses to cirrhosis and hepatocellular carcinoma. Dual energy CT allows the discrimination of substance using monochromatic image (MI), and steatosis exhibit specifically the CT value of each energy level. The purpose is to evaluate the fat quantification in the liver using spectral HU curve and CT value compare to a conventional image diagnosis. METHODS: Dual energy CT and liver biopsy were performed in 54 patients between October 2014 and April 2016. The CT value of 40 keV MI was measured by spectral HU curve setting 3 points ROI on the right and left liver. The CT value of 40 keV MI was compared with steatosis area and the NAFLD activity score (NAS). Additionally, steatosis area was compared with the conventional CT value scan and hepatorenal echo contrast value. RESULTS AND DISCUSSION: The CT value of 40 keV MI exhibited a negative correlation for the stenosis area (R2=0.619), and NAS (R2=0.147). Steatosis area exhibited correlation for the conventional CT value (R2=0.407), and hepatorenal echo contrast (R2=0.135). This study suggests that the evaluation of the fat quantification in the liver using the spectral HU curve and CT value improved in comparison to the conventional image diagnosis.

[Usefulness of the Training of Trigger Point in Coronary CT Using Test Bolus Tracking Method].

BACKGROUND: Test bolus tracking (TBT) method has been used in coronary CT examination, because it is possible to examine the optimum contrast timing. However, the scan timing highly depends on an operators' recognition of peak in test bolus, thus there is a possibility of variation in contrast effect. PURPOSE: The aim of this study is to improve the variation of contrast effect among the operators. METHODS: The training for the operators was conducted to acknowledge them the optimal trigger points. The mean CT value and standard deviation of the ascending aorta were calculated to compare before and after the training. RESULTS: The mean CT value of the ascending aorta after the training was 485.02±73.06 HU, compared to 462.53±78.26 HU before the training. Standard deviation was significantly lower than before the training. CONCLUSION: The variation of contrast effect between the operators has been reduced by the training, and reproducibility of the examination has been improved.